Does Exposure and Receptivity to E-cigarette Advertisements Relate to E-cigarette and Conventional Cigarette Use Behaviors among Youth? Results from Wave 1 of the Population Assessment of Tobacco and Health Study

Background: E-cigarettes (EC) are the most commonly used tobacco product among youth. Additionally, youth EC users are progressing to smoking conventional cigarettes (CC). Although known to target youth, there are no current restrictions in the US on EC marketing, including advertising. The purpose of this study is to evaluate the relationship between EC advertisements and youth EC and CC use behaviors. Methods: This study analyzed data from youth (12-17 years) aware of EC in Wave 1 (2013-2014) of the Population Assessment of Tobacco and Health (PATH) study (n=12,199). Weighted logistic regression models assessed whether exposure and receptivity to any of five randomized EC ads (two TV and three print) were associated with the outcomes of EC and CC behaviors of ever use, current (past 30 day) use, and susceptibility to future use. Additional analyses determined whether EC advertising exposure and EC and CC behaviors associations were moderated by EC advertising receptivity. All models were adjusted for sociodemographics, other combustible tobacco product use, and parent smoking. Results: EC advertisement exposure was significantly associated to ever and current EC use as well as susceptibility to EC and CC (p Conclusion: These findings demonstrate exposure to EC advertisements are particularly associated with EC use behaviors, but could play a role in future CC use as well. Youth who are receptive to EC advertisements appear particularly vulnerable. Further studies should focus on the role of receptivity to EC advertisements among youth in order to support regulatory policy targeting EC advertising

CO mapping of the Orion molecular cloud: The influence of star formation on cloud structure

Regions of massive star formation have long been believed to have a profound influence on the structure of their surrounding molecular clouds. The ways in which massive star formation has altered the structure and kinematics of the Orion Molecular Cloud are discussed. The data to be discussed consists of a large scale map of the CO J=1-0 emission from approximately 3 square degrees of OMC-1. During 1985, the Five College Radio Astronomy Observatory 14M antenna was used to map a 2 deg x 1 deg region centered on alpha(1950) = 5(h)33(m)00(s) delta(1950) = -5 deg 30 min. The region mapped in 1985 covers the well known HII regions M42, M43, and NGC1977, and the CO map contains abundant evidence of the interaction between these regions and the molecular cloud. Indeed, the global structure of the cloud appears to have been strongly influenced by the continuous formation of massive stars within the cloud. Individual instances of some of these features are discussed. There appear to be two classes of features which are indicative of this interaction: CO bright rims and CO holes. During 1986, we have undertaken further mapping of OMC-1 to the south of the region covered by the 1985 map. This portion of the cloud contains significant regions of star formation, but O star formation has not occured and large HII regions have not developed to alter the appearance of the cloud. A detailed map of this region is thus an opportunity to view the structure of the molecular cloud before it has been altered by massive star formation. Preliminary analysis of data obtained in this region suggests that the structure and kinematics of the southern portion of the Orion cloud are indeed dramatically different from those of the region previously mapped. Comparison of the two regions thus supports models of the development of structure in molecular clouds through interaction with the HII regions formed within them

Striations in the Taurus molecular cloud: Kelvin-Helmholtz instability or MHD waves?

The origin of striations aligned along the local magnetic field direction in the translucent envelope of the Taurus molecular cloud is examined with new observations of 12CO and 13CO J=2-1 emission obtained with the 10~m submillimeter telescope of the Arizona Radio Observatory. These data identify a periodic pattern of excess blue and redshifted emission that is responsible for the striations. For both 12CO and 13CO, spatial variations of the J=2-1 to J=1-0 line ratio are small and are not spatially correlated with the striation locations. A medium comprised of unresolved CO emitting substructures (cells) with a beam area filling factor less than unity at any velocity is required to explain the average line ratios and brightness temperatures. We propose that the striations result from the modulation of velocities and the beam filling factor of the cells as a result of either the Kelvin-Helmholtz instability or magnetosonic waves propagating through the envelope of the Taurus molecular cloud. Both processes are likely common features in molecular clouds that are sub-Alfvenic and may explain low column density, cirrus-like features similarly aligned with the magnetic field observed throughout the interstellar medium in far-infrared surveys of dust emission.Comment: 11 pages, 4 figures. Accepted for publication in MNRA

SWAS observations of comet 9P/Tempel 1 and Deep Impact

On 4 July 2005 at 1:52 UT the Deep Impact mission successfully completed its goal to hit the nucleus of 9P/Tempel 1 with an impactor, forming a crater on the nucleus and ejecting material into the coma of the comet. The 370 kg impactor collided with the sunlit side of the nucleus with a relative velocity of 10.2 km/s. NASA's Submillimeter Wave Astronomy Satellite (SWAS) observed the 1(10)-1(01) ortho-water ground-state rotational transition in comet 9P/Tempel 1 before, during, and after the impact. No excess emission from the impact was detected by SWAS. However, the water production rate of the comet showed large natural variations of more than a factor of three during the weeks before the impact.Comment: to appear in the proceedings of the IAU Symposium No. 231: "Astrochemistry - Recent Successes and Current Callenges". Typo corrected in author affiliation lis

Spitzer spectral line mapping of supernova remnants: I. Basic data and principal component analysis

We report the results of spectroscopic mapping observations carried out toward small (1 x 1 arcmin) regions within the supernova remnants W44, W28, IC443, and 3C391 using the Infrared Spectrograph of the Spitzer Space Telescope. These observations, covering the 5.2 - 37 micron spectral region, have led to the detection of a total of 15 fine structure transitions of Ne+, Ne++, Si+, P+, S, S++, Cl+, Fe+, and Fe++; the S(0) - S(7) pure rotational lines of molecular hydrogen; and the R(3) and R(4) transitions of hydrogen deuteride. In addition to these 25 spectral lines, the 6.2, 7.7, 8.6, 11.3 and 12.6 micron PAH emission bands were also observed. Most of the detected line transitions have proven strong enough to map in several sources, providing a comprehensive picture of the relative distribution of the various line emissions observable in the Spitzer/IRS bandpass. A principal component analysis of the spectral line maps reveals that the observed emission lines fall into five distinct groups, each of which may exhibit a distinct spatial distribution: (1) lines of S and H2 (J > 2); (2) the H2 S(0) line; (3) lines of ions with appearance potentials less than 13.6 eV; (4) lines of ions with appearance potentials greater than 13.6 eV, not including S++; (5) lines of S++. Lines of group (1) likely originate in molecular material subject to a slow, nondissociative shock that is driven by the overpressure within the supernova remnant, and lines in groups (3) - (5) are associated primarily with dissociative shock fronts with a range of (larger) shock velocities. The H2 S(0) line shows a low-density diffuse emission component, and - in some sources - a shock-excited component.Comment: 43 pages, including 21 figures. Accepted for publication in Ap

Sensitive Limits on the Water Abundance in Cold Low Mass Molecular Cores

We present SWAS observations of water vapor in two cold star-less clouds, B68 and Core D in rho Ophiuchus. Sensitive non-detections of the 1(10)-1(01) transition of o-H2O are reported for each source. Both molecular cores have been previously examined by detailed observations that have characterized the physical structure. Using these rather well defined physical properties and a Monte-Carlo radiation transfer model we have removed one of the largest uncertainties from the abundance calculation and set the lowest water abundance limit to date in cold low-mass molecular cores. These limits are < 3 x 10^{-8} (relative to H2) and < 8 x 10^{-9} in B68 and rho Oph D, respectively. Such low abundances confirm the general lack of ortho-water vapor in cold (T < 20 K) cores. Provided that the ortho/para ratio of water is not near zero, these limits are well below theoretical predictions and appear to support the suggestion that most of the water in dense low-mass cores is frozen onto the surfaces of cold dust grains.Comment: 12 pages, 3 figures, accepted by Astrophysical Journal Letter

Validation of magnetophonon spectroscopy as a tool for analyzing hot-electron effects in devices

It is shown that very high precision hot-electron magnetophonon experiments made on n+n−n+-GaAs sandwich device structures which are customized for magnetoresistance measurements can be very accurately modeled by a new Monte Carlo technique. The latter takes account of the Landau quantization and device architecture as well as material parameters. It is proposed that this combination of experiment and modeling yields a quantitative tool for the direct analysis of spatially localized very nonequilibrium electron distributions in small devices and low dimensional structures

Distribution of Water Vapor in Molecular Clouds

We report the results of a large-area study of water vapor along the Orion Molecular Cloud ridge, the purpose of which was to determine the depth-dependent distribution of gas-phase water in dense molecular clouds. We find that the water vapor measured toward 77 spatial positions along the face-on Orion ridge, excluding positions surrounding the outflow associated with BN/KL and IRc2, display integrated intensities that correlate strongly with known cloud surface tracers such as CN, C2H, 13CO J =5-4, and HCN, and less well with the volume tracer N2H+. Moreover, at total column densities corresponding to Av < 15 mag., the ratio of H2O to C18O integrated intensities shows a clear rise approaching the cloud surface. We show that this behavior cannot be accounted for by either optical depth or excitation effects, but suggests that gas-phase water abundances fall at large Av. These results are important as they affect measures of the true water-vapor abundance in molecular clouds by highlighting the limitations of comparing measured water vapor column densities with such traditional cloud tracers as 13CO or C18O. These results also support cloud models that incorporate freeze-out of molecules as a critical component in determining the depth-dependent abundance of water vapor

C18O (3-2) observations of the Cometary Globule CG 12: a cold core and a C18O hot spot

The feasibility of observing the C18O (3-2) spectral line in cold clouds with the APEX telescope has been tested. As the line at 329.330 GHz lies in the wing of a strong atmospheric H2O absorption it can be observed only at high altitude observatories. Using the three lowest rotational levels instead of only two helps to narrow down the physical properties of dark clouds and globules. The centres of two C18O maxima in the high latitude low mass star forming region CG 12 were mapped in C18O (3-2) and the data were analyzed together with spectral line data from the SEST. The T_MB(3-2)/T_MB(2-1) ratio in the northern C18O maximum, CG 12 N, is 0.8, and in the southern maximum, CG 12 S, ~2. CG 12 N is modelled as a 120'' diameter (0.4pc) cold core with a mass of 27 Msun. A small size maximum with a narrow, 0.8 kms-1, C18O (3-2) spectral line with a peak temperature of T_MB ~11 K was detected in CG 12 S. This maximum is modelled as a 60'' to 80'' diameter (~0.2pc) hot (80 K < Tex < 200 K) ~1.6 Msun clump. The source lies on the axis of a highly collimated bipolar molecular outflow near its driving source. This is the first detection of such a compact, warm object in a low mass star forming region.Comment: APEX A&A special issue, accepte

Minimum sample size for external validation of a clinical prediction model with a continuous outcome.

Clinical prediction models provide individualized outcome predictions to inform patient counseling and clinical decision making. External validation is the process of examining a prediction model's performance in data independent to that used for model development. Current external validation studies often suffer from small sample sizes, and subsequently imprecise estimates of a model's predictive performance. To address this, we propose how to determine the minimum sample size needed for external validation of a clinical prediction model with a continuous outcome. Four criteria are proposed, that target precise estimates of (i) R2 (the proportion of variance explained), (ii) calibration-in-the-large (agreement between predicted and observed outcome values on average), (iii) calibration slope (agreement between predicted and observed values across the range of predicted values), and (iv) the variance of observed outcome values. Closed-form sample size solutions are derived for each criterion, which require the user to specify anticipated values of the model's performance (in particular R2 ) and the outcome variance in the external validation dataset. A sensible starting point is to base values on those for the model development study, as obtained from the publication or study authors. The largest sample size required to meet all four criteria is the recommended minimum sample size needed in the external validation dataset. The calculations can also be applied to estimate expected precision when an existing dataset with a fixed sample size is available, to help gauge if it is adequate. We illustrate the proposed methods on a case-study predicting fat-free mass in children